Solvent extraction of oils



Aug. 31, 1937.

F. w. SULLIVAN, JR, L-r AL 2,091,400

SOLVENT EXTRACTION OF OILS Filed March 22. 1953 Inventor's:-

Frcder'z'cfn WfiQZZiOOJgJZ' WILLZiQmJi. baizllce firtluu'b. Drown Fred FDL'w 0129 ATTORNEY STATES FATE 2,09LMO SOLVENT EXTRACTION 0F OILS Frederick W. Sullivan, .lr., William H. Bahlke, and Arthur B. Brown, Hammond, Ind., and Fred F. Diwoky, Chicago, 11]., assignors to Standard Oil'Company, Chicago, 111., a corporation of Indiana Application March 22,

1933, Serial No. 662,133

In France March 23, 1932 16 Claims.

This invention relates to a process for extracting hydrocarbon oils withvorganic solvents and it pertains more particularly to the use of certain oxygenated-halogen organic solvents for extracting mixed base oils and naphthas.

One object of our process is to provide a process for extracting objectionable substances from hydrocarbon oils and particularly lubricating oils, whereby the oils will have improved properties.

A further object of our invention is to provide a process for extracting the unsaturated and aromatic compounds from low boiling hydrocar-.

bons such as naphthas.

One application of our invention provides an improved process for treating light hydrocarbon distillates, such as kerosene and burning oils, whereby the naphthenic hydrocarbons, sulfur compounds and other objectionable substances can be removed. Our extraction process is used to replace the acid treatment generally applied to light hydrocarbon distlllates. Wemay also employ our process for extracting the naphthenic and unsaturated hydrocarbons from gasoline,

naphthas and particularly the cracked naphthas to obtain a concentrate of compounds that have improved antiknock properties.

A further specific object of our invention is to provide a process for extracting objectionable substances from lubricating oils whereby the oils will have improved viscosity characteristics, for example, such as is shown by the viscosity index.

A further object of our invention'isto provide an improved process for treating mixed base petroleum oils without the nuisance and expense of acid treatment, and without the loss of valuable petroleum constituents which accompanies the use of acid treating. A further object is to provide a lubricating oil with a minimum tendency toward sludge formation when exposed to oxidizing conditions. Other objects will be apparent as the detailed description of our invention proceeds.

The expression viscosity index, as used herein, refers specifically to the index defined by Dean & Davis in Chemical & Metallurgical Engineering, vol. 38, page 618, 1929. The viscosity index of the lubricating oil is an indication of its composition or type, that is, whether it is a parafiin base or naphthenic base oil. Parafiin base oils are arbitrarily assigned a viscosity index of 100. Naphthenic base oils are assigned a viscosity index ofzero, and mixed base oils lie between these extremes. When our invention is applied to mixed base lubricating oils, the object is to obtain from these lubricating oils a maximum yield of paramn-type oils (with a high viscosity index) without the nuisanceor cost of acid treating, and without appreciable destruction of the naphthenic constituents of the oil.

We have discovered that certain oxygenatedhalogen organic compounds, such as halogenated ketones, for example, di-(2-chlorethy1) ketone; halogenated acetals, for example, dichlorethylidene diethyl ether; halogenated aldehydes, for example, ortho-chlorbenzaldehyde and chloral; and halogenated ketols and the like, have remarkable properties for the extraction of undesirable substances such as naphthenic compounds, from hydrocarbon oils. Examples ,of these hydrocarbon oils are the naphthas and mixed base lubricating oils. In describing one of .the preferred embodiments'of our invention we will illustratein detail the use of di-(2-chlorethyl) ketone in the process of extracting the undesirable compounds from a mixed base lubricating oil. It should be understood that other compounds selected from the above classes and equivalent classes of compounds may be used in the following example, instead of the chlorinated ketones, without departing from the scope of our invention. Also these chlorinated ketones may be used to extract the antiknock fraction of compounds, such as the unsaturated and naphthenic hydrocarbons, from low boiling mineral oils such as naphtha and cracked naphtha.

In the accompanying drawing which forms a part of this specification, we have shown diagrammatically, an elevational plan view of an apparatus which is" suitable for carrying out our process. Our invention is applicable to the treatment of any mixed base mineral oil or naphtha, but in our preferred embodiment we have described the treatment of a heavy untreated lubricating distillate having a viscosity of about 102 seconds Saybolt at 210 F., a gravity of about 21.3 A. P. I. and a Dean & Davis viscosity index of about 58. We will also disclose the use of a batch process wherein equal amounts of the solvent and oil are mixed and separated in successive steps, but it will be apparent that we may also use a continuous process and extract the oil with the solvent counter-currently.

The mixed base lubricating oil may be introduced by a pipe I0 into extractor II which is provided with suitable agitating means, such as the stirrer l2. A pulley I20, is provided on the stirrer so that it may be driven by a belt or some suitable means. A closed coil I3 is provided on the inside of the extractor, said coil being pro-- vided with connections whereby it may be heated with steam from pipe 54 or cooled with water, brine or a suitable refrigerant from pipe 95. The base or the extractor is preferably conical and it terminates in a discharge pipe "3 which preferably has a glass window ll therein so that the liquids flowing through the pipe may be seen.

After the extraction, which will be described later, the solvent and naphthenic extract are withdrawn through pipe l8 and valve it to still 20, the extract being removed from the still through pipe 2 l The solvent is distilled from the extract and passes up through the fractionating tower 22, around the reflux coils 23, through pipe 2 3, condenser 25, and pipe to storage tank fi'l, from which it may be introduced into the extractor by means of pipe 28 in amounts regulated by valve 29. A suitable venting device Zia is provided on the storage tank 27. The vacuum pump 24a, which is connected in the line 2 5, may be used to reduce the pressure in still 26, thereby enabling the solvent to be distilled at a lower temperature than would be necessary if the distillation were performed at atmospheric pressure. It

. is particularly desirable to use vacuum distillation when high boiling solvents, that decompose upon heating, are used to extract the oils.

The residual oil or rafflnate is withdrawn through pipe 3!) and valve 3! into the stripping.

vent, is withdrawn through pipe 3d and valve 3%.

The chlorinated ketone and stripping medium are removed from the stripper by pipe 36, passed to the condenser 21, and thence to the separator 38 where the'stripping medium is separated from the oil. A valved vent 38a is provided on the separator to remove the condensed steam or gaseous stripping medium. The solvent is returned by the pump 39 and line 40 to storage tank 27. We introduce equal parts of the untreated. viscous oil, hereinabove described, and di(2-chlorethyl) ketone into extractor H. We then introduce steam in coils l3 to raise the temperature high enough to obtain complete miscibility between'the oil and dichloracetone. In this particular example we use a temperature of about 100 F., but the temperature may vary considerably with the different oils, the preferred range being about 50-200 F. However, when our process is used to extract the antiknock fraction of hydrocarbons from low boiling oils such as naphthe, it is not necessary to heat the solvent and naphtha in order to obtain miscibility. Generaloil and the selectivity of the solvent.

ly,' the solvent is miscible with the naphthas at temperatures within the range of 10 to +10 F. During the first step, the oil and solvent may be thoroughly mixed by the agitator It. In fact, if the agitation is sufliciently complete the temperature need not be raised to efiect miscibility. It is very important, however, to obtain thorough contact of oil with solvent. After the solvent has been thoroughly mixed with the oil we cool the mixture to decrease the amount of oil dissolved in the extract. Cooling may be effected by passing cold water brine or other refrigerants through coils I3, the agitation being preferably continued during the cooling step. It appears that the temperature to which the mixture is cooled has a marked effect upon the yield of paraflinic-type The yield of oil or raf'finate increases as the temperature of the mixture undergoing separation decreases.

aoersoo From 35 to F. this change is closely proportional in magnitude to the temperature change. At higher temperatures the decrease in yield is more rapid than the increase in temperature.

After cooling, the oil and solvent are allowed to separate, which separation may require from onefourth hour to four or five hours at temperatures from F. to 35 F., and we prefer to use the lower temperature and longer periods of separation. If the oil has not been dewaxed the upper oil layer may solidify on cooling, the lower chloracetone layer being substantially wax-free and fluid; usually both the oil and solvent will be in liquid state. The extract layer is removed by opening valves Eta and i9, and when the oil layer appears in the'sight glass ll, valve Mia is closed. We then close valve it and open valves ltd and Si and pass the remaining oil or rafiinate into the stripping column 32, as hereinabove described. Or we may extract theoil a second time with the same solvent or a different solvent as many times as desired to effect the degree of refining required. In this case we may employ the subsequent extracts to initially treat a new batch of raw oil in the manner known to the art, Also,

. with highly volatile solvents, the extraction may be performed under pressure, and in such processes the pump 9 can be used to force the solvent into extractor ii. The extraction may be performed at any pressure, but preferably at a pressure within the range of one to fifty pounds per square inch.

The operating temperatures of still 2%, column 22 and stripper 32, the number of fractionating plates, the amount of refluxing, etc.'may' be determined by anyone skilled in this art, and since they form no part of the present invention, they will not be described in detail. In fact, we may draw the oil from the top of the extractor by suitable draw-off pipes, and we may then use the extractor itself as a steam still for separating the chlorinated ketone from the extract; a suitable vapor take-0d pipe and condenser being provided between the extractor and the solvent storage tank 27. Other expedients will be apparent'to those skilled in the art.

Other chlorinated ketones may be used as solvents for extracting mixed base hydrocarbon oils and these chlorinated ketones may be used in substantially the same manner as described above in connection with di(Z-chlorethyl) ketone. The chlorinated ketones given below are-representative of the class of ketones suitable for our invention. Some of the chlorinated ketones set forth have boiling points substantially above and some have boiling points substantially below the easily determined by those skilled in the art.

Most of the ketones suitable for our invention have the general formula RCO-R1,- wherein R represents an organic residue which may or may not be chlorinated, and R1 represents a chlorinated organic residue. We may also use chlorinated diketones of the general formula R-COCOR1 wherein It represents an organic residue that may or may not be chlorinated, and R1 representsa chlorinated organic residue. R2, R3, and R4 repana Ra-CO-Rs-CO-Rz;

resent organic residues, any one of these or any combination of which may be chlorinated. We have found that the alpha monochlorinated ketones are generally unstable when distilled from the oils, and we prefer to use the polychlorinatcd carbonyl compounds and carbonyl compounds having the chlorine atom more than one carbon the beta and gamma derivatives. Examples of the chlorinated ketones that are suitable for our invention are: trichlor acetone, 2-chlorethyl methyl ketone, methyl 2-2-dichlorethyl ketone, dichloro biacetyl, chloro cyclobutanone, 2-trichlorethyl methyl ketone, acetone chloroform, methyl chlorisopropyl ketone, 2-dichloropropyl methyl ketone, trichlorisopropyl methyl ketone, ethyl-Z-chlor ethyl ketone, 2-chlorpropyl methyl 15 ketone, ethyl 2-dichlorethyl ketone, 3-chloropropyl methyl ketone, methyl trichlorisopropyl ketone, di(2-2-dichlorethyl) ketone, methyl 3- chlorbutyl ketone, methyl 2-dichlorbutyl ketone, 2-chlorethylisopropyl ketone, ethyl trichloriso- 20 propyl ketone, ethyl dichlorisopropyl ketone and the like.

As a further example of chlorinated compounds suitable for extracting mineral oils, such as naphthas and lubricating oils, we may use the chlorinated acetals. Most of the halogenated acetals suitable for our invention have the following general formula:

and R2 represent alkyl residues, and any one com bination on all three of said residues may be chlorinated. The examples of the chlorinated 35 acetals that are suitable for our invention are:

chloromethylene di methyl ether), chloromethylene di(ethyl ether), chloro methylene di(2- chlorethyl ether), di and trlchloracetals or polychloro acetals, 'ethylidene di(2-chlorethyl ether), 40 ethylidene di(chloropropyl ether), chlorethylidene di(methyl ether), dichlorethylidene di(ethyl ether),- dichlorethylidene di(methyl ether), and the like.

The chlorinated aldehydes suitable for our in- 45 vention have the general formula R-CHO wherein R represents a chlorinated organic residue. Examples of the chlorinated halides suitable for our invention are: mono, di and trichloracetaldehyde, 2-chloropropionic aldehyde, 2-dichlorpro- 50 picnic aldehyde, 2-3-dichlorbutyraldehyde,' 2-3-3- trichlorbutyraldehyde, 2-chlorobutyraldehyde, 3- chlorbutyraldehyde, ortho, meta and para chlorobenzaldehyde and the like.

It should be understood that the compounds set 55 forth in this application are representative of the general class of compounds suitable for our invention and that other chlorinated derivatives, homologs and isologues of the compounds set forth may be used as solvents for extracting min- 60 eral oils. Also, the compounds set forth hereinabove and their equivalents may or may not be used in the anhydrous form. Generally, the above compounds may beused'in the commercial forms. As a further modification-of our invention we may use mixtures of the solvents set forth above and we have found it desirable to mix those solvents which have boiling points that are substantially the same.

It should be understood that the mineral oil to 70 be extracted, or the solvents, may be mixed with other solvents or diluents such as propane, butane, propylene, naphtha, acetone, etc. for the purpose of efiecting a better and quicker separation of the liquid phases. Also, these-diluents 75 tend to reduce the viscosity of the oil-and. en-

atom removed from the carbonyl group, such as quantity of the propane with the aid of a. suitable vent disposed in the top part of the extrac tor ii, we can eifect sufiicient cooling so that it will not be necessary to employ the coohng coils I3. Chlorinated hydrocarbons, such as ethylene dichloride and the like, may also be used in combination with the solvents hereinabove described.

The volume of solvent used to extract the oil may vary with the selectivity of the particular solvent; however, from one to two volumes of solvent for each volume of oil will give satisfactory results. It should be understood that larger volumes, for example four or five volumes, of solvent may be used for each volume of oil. When mixed solvents are used to extract a lubricating oil we may use equal proportions of the solvent or we may use more of one solvent thanthe other.

We do not limit ourselves to any theory or explanation of why the compounds set forth hereinabove are suitable extracting agents, but experiments have shown that the above general classes of compounds are in a class by themselves and that they produce results of an entirely different order from the results produced by other well known solvents.

Instead of using the extraction process as a sole means for treating the oil, it may be used to supplement a preliminary acid treatment. The preliminary acid treat may; for instance, be desirabl e for separating the tarry materials that would be undesirable in the naphthenic extract.

We preferably follow the extraction process with a light sulfuric acid treat to improve color. the oil may be clay treated, such as by percolation or contacting with fine clay at elevated temperatures in order to improve the color andsludge stability of the oil. If the oil was initially dewaxed, it will be in a finished condition after the clay treatment.

A very important characteristic of the oils produced by our improved extraction process is their ability to resist oxidation and sludge formation. This abnormal freedom from sludge formation is probably due to the removal of certain potential sludge-forming ingredients in the oil, and while Also we do not understand the exact phenomena, ex-

periments have proved the superior. sludge resistant properties ofour finished lubricating oil. For instance, an oil which, when acid treated, has a sludge time of about 22 hours and a deteriorationtime of 47 hours has, when extracted in accordance with our invention, a sludging time of more than hours and a deterioration time of more than hours. Many modifications of our invention will beapparent to those skilled in the art, for instance, we may heat a mixture of oil and solvent to a miscibility temperature (say 150 F.) and then, instead of making a single separation, we may separate the oil in consecutive steps as the temperature is lowered (say at F., 80 F. a'nd'35 F.). The final separation temperature may be below the pour point of the oil layer.

As stated above, the solvents and processes set forth hereinabove may be used to extract naphthas, kerosene, gasoline and the like for the purpose of removing the naphthenic and unsaturated compounds in these hydrocarbon distillates.

- range of about 250 to 350 F. and an end boiling point within the range of 360 to 400 F., the

boiling point of the solvent should be somewhat below the initial boiling point of said naphtha.

As a modification of our process, we may extract naphthas with solvents that boil above the end point of the naphtha. For example, if the naph= 20 tha has an end point within the range of 200 to 280 R, we may use a solvent that boils above the end point of said naphtha. In this modification of our invention it is apparent that the extract must be distilled from the solvent in still Similarly, the railinate is distilled from the solvent in the stripper 32. connected from the tank 2! and diverted to a storage tank, not shown, for collecting the extract. Similarly, the conduit 40 is disconnected from tank 27 and diverted to a storage tank, not shown, to collect the ramnate. The solvent is removed from conduits 2i and 3d and returned to the tank 21 for further use in the extraction of the oils.

As a second modification of our invention, the naphthas may be extracted with solvents that boil at a temperature between the initial and end boiling point of the naphtha. In such cases the solvent and extract or solvent and rafinate cannot be separated by distillation and other methods must be adopted to separate the solvent from the extract and railinate. For example, a 50 to 80% solution of methyl or ethyl alcohol or other suitable solvents may be added to the extract layer in order to effect a separation of the solvent from the extract.-

Although the details of our invention have been described by giving examples of processes for extracting mixed base lubricating oils, it should be understood that anyone skilled in the art can modify the above examples and extract the light hydrocarbon distillatesaccording to the teachings of this invention. While we have described the preferred embodiment of our invention, it should be understood that we do not limit ourselves to any of the details hereinabove set forth, except as defined by the following claims which should be construed as broadly as the prior art will permit.

We claim:

1. The method oi? removing naphthenic compounds and unsaturated compounds from a mixed base lubricating oil which comprises heating and agitating the oil with a polychlorinated organic compound containing a carbonyl group,

cooling the oil and solvent until separation of paraflinic compounds from the solvent and dissolved compounds occurs, and separating the sl=- vent together with the dissolved compound from the treated oil.

2. The method of preparing lubricating oils having a high viscosity index and which are stable against sludge formation, which comprises mixing a mixed base lubricating oil with an organic solvent selected from the group consisting The conduit 25 is diseans-cc of polychlorlnated ketones containing not more than six carbon atoms, chlorinated aldehydes containing not more than four carbon atoms and chlorinated acetals containing not more than eight carbon atoms, heating the oil and solvent to obtain substantial miscibility, cooling said mixture of oil and solvent until separation of par- 3. The method of extracting unsaturated compounds from a mineral oil distillate containing unsaturated compounds and parafiinic cornpounds, which comprises mixing the oil with an organic solvent selected from the group consisting of polychlorinated aliphatic ketones containing not more than six carbon atoms, chlorinated aliphatic aldehydes containing not more than four carbon atoms and' chlorinated aliphatic acetals containing not more than eight carbon atoms, cooling the mixture of oil and solvent until separation of paraflinic compounds from the solvent and dissolved unsaturated compounds occurs, and separating the solvent together with the dissolved compounds from the treated oil.

4. The method of extracting unsaturated hydrocarbons from a hydrocarbon oil distillate containing unsaturated hydrocarbons and paraiiinic hydrocarbons, which'comprises mixing the distillate with a polychlorinated aliphatic ketone containing not more than six carbon atoms, cooling said mixture of distillate and solvent until separation of paraflinic hydrocarbons from the solvent and dissolved unsaturated hydrocarbons occurs, and separating the solvent together with the dissolved hydrocarbons from the treated hy-- drocarbon oil distillate.

5. The method of extracting unsaturated hydrocarbons from a hydrocarbon oil distillate containing unsaturated hydrocarbons and paraiiinic hydrocarbons, which comprises mixing said oil with a solvent containing a beta-chlorinated aliphatic ketone containing not more than six carcarbonyl compound containing not more than eight carbon atoms, cooling the mixture of oil and solvent until separation of parafiinic compounds from the solvent and dissolved unsaturated compounds occurs, and separating the solvent together with the dissolved compounds from the treated .oil.

'7. The method of removing naphthenic compounds and unsaturated compoimds from a mixed base lubricating oil which comprises contacting a mixed base lubricating oil with a solvent containing a chlorinated aldehyde containing not more than four carbon atoms, heating and agitating the oil and solvent to obtain substantial miscibility, cooling the oil and solvent until separation of paraflinic compounds from the solvent and dissolved compounds occurs, and separating the solvent together with the dissolved compounds from the treated oil.

8. The method of removing naphthenic compounds from a mixed base lubricating oil which comprises heating and agitating the oil with a polychlorinated aliphatic aldehyde containing not more than four carbon atoms, cooling the oil and solvent until separation of paraffinic compounds from the solvent and dissolved naphthenic compounds occurs, and separating the solvent together with the dissolved naphthenic compounds from the treated oil.

9. 'The method of removing naphthenic compounds from a mixed base lubricating oil, which comprises heating and agitating the oil with a solvent containing a beta-chlorinated aliphatic aldehyde containing not more than four carbon atoms, cooling the oil and solvent until separation of parafiinic compounds from the solvent and dissolved naphthenic compounds occurs, and separating the solvent together with the dissolved naphthenic compounds from the treated oil.

' 10. The method of extracting unsaturated hydrocarbons from a hydrocarbon oil distillate containing unsaturated hydrocarbons and paramnic hydrocarbons, which comprises mixing the oil with a solvent containing a chlorinated aldehyde containing not more than four carbon atoms,

cooling the mixture of oil and solvent until separation of paramnic hydrocarbons from the solvent and dissolved unsaturated hydrocarbons occurs, and separating the solvent together with the dissolved compounds from the treated oil.

11. The method of extracting unsaturated compounds from a mineral hydrocarbon oil distillate containing unsaturated compounds and aliphatic compounds, which comprises mixing the oil with a solvent containing a beta-chlorinated aliphatic aldehyde containing not more than four carbon atoms, cooling the mixture of oil and solvent until separation of paraifmic compounds from the solvent and dissolved unsaturated compounds occurs, and separating the solvent together with the dissolved unsaturated compounds from the treated oil.

12. The method of removing naphthenic compounds from a mixed base lubricating oil, which comprises heating and agitating the oil with a solvent containing a chlorinated acetal containing not more than eight carbon atoms, cooling the oil'and solvent until separation of paraflinic compounds from the solvent and dissolved naphthenic compoundsoccurs, and separating the solvent together with the dissolved compounds from the treated oil. I

13. The method of extracting unsaturated hydrocarbons from a mineral hydrocarbon oil distillate containing unsaturated hydrocarbons and parafiinic hydrocarbons, which comprises mixing the oil with a solvent containing a chlorinated acetal containing not more than six carbon atoms, cooling said oil and solvent until separation of paraflinic hydrocarbons from the solvent and dissolved unsaturated hydrocarbons occurs, and separating the solvent together with the dissolved unsaturated hydrocarbons from the treated oil.

14. The method of extracting unsaturated compounds from a hydrocarbon oil distillate containing unsaturated compounds and aliphatic hydrocarbons, which comprises mixing the oil with an organic solvent containing a polychlorinated aliphatic acetal containing not more than six carbon atoms, cooling the mixture of oil and solvent until separation of paraifinic compounds from the solvent and dissolved unsaturated compounds occurs, and separating the solvent together with the dissolved compounds from the treated oil.

15. The process of extracting unsaturated hy-- drocarbons from petroleum naphtha containing unsaturated hydrocarbons and paraifinic compounds, which comprises mixing the naphtha with an organic solvent selected from the group consisting of polychlorinated aliphatic ketones containing not more than six carbon atoms, chlorinated aliphatic aldehydes containing not more than four carbon atoms and chlorinated aliphatic acetals containing not more than six carbon atoms, cooling the mixture of naphtha and solvent until separation of paraifinic compounds from the solvent and dissolved unsaturated hydrocarbons occurs, and separating the solvent together with the dissolved unsaturated hydrocarbons from the treated naphtha.

16. The method of preparing lubricating oils having a high viscosity index and which are stable against sludge formation, which comprises mixing a mixed base lubricating oil with a beta chlorinated aliphatic ketone containing not more than six carbon atoms, heating the oil and chlorinated ketone to obtain substantial miscibility, cooling said mixture of oil and chlorinated ketone until separation of parafiinic compounds from the chlorinated ketone and dissolved compounds occurs, separating the chlorinated ketone together with the dissolved compounds from the treated oil.

FREDERICK W. SULLIVAN, JR. WILLIAM H. BAHLKE. AR'IHUR B. BROWN.

FRED F. DIWOKY. 

